Vocabulary

Targeted market

3D Printing within construction can be divided into various markets that a company can focus on.

These include:

Printers - The company manufactures 3d printers of a large scale to sell them.

Printer parts - The company makes components for large scale printers.

Materials - The company produces raw materials to be used by large scale 3d printers made by other companies.

Furniture/Sculptures - The company has its own printers, and provides only the printing service for smaller objects, which can include furniture or sculptures.

Building components - The company has its own printers, and provides printing services of
larger building components (such as walls, floors, etc.) at the customer request. This can
include whole buildings, but sliced into large components that need to be assembled on
site.

Building projects - The company is involved in constructing buildings partially or fully through 3D printing. The whole process of creating the structure of the building is performed by the company, which can also include the design part.

Development stage of printers

The current stage of development of the printer machine.

Conceptual - The company has no working large scale 3d printer, but is limited only to conceptual designs.

Prototype - The company has one or more prototypes of the machine under construction. The machines are partially working or in need of crucial improvements.

Working product - The company has one or more fully functional products. Their design and function is proven through several successful test prints.

Commercial products - The company sells fully functional printers. This category is limited to companies that have already sold some of their printing machines.

Development stage of printed materials

The current development stage of the printed materials.

Conceptual - No physical prints have been carried out up to date.

Prototypes / Test prints - The material has only been printed a limited number of times, to
prove the functioning of the printing machine.

Usable product - The material has been printed several times, and its characteristics and behavior are known to the company. Various objects have been produced already.

Commercial product - The printed material has been sold commercially by the company.

Largest print up to date (by size)

The size of the largest printed part or building up to date expressed in cubic meters.

Largest print up to date (by category)

The size of the largest prints that the company made, divided into categories according to their size.

Minor test prints - The company has only printed some test prints in very small scale, up to 0.5m in each dimension, mostly for testing the material or proving the concept.

Furniture/Sculptures - The company has printed elements of a scale of around 1m3 (1m in each size), such as furniture elements, sculptures and similar.

Building elements - The company has successfully printed elements for houses.

Less than 50m2 buildings - The has printed actual building with a 50m2 or less footprint.

Less than100m2 buildings - The company has printed actual buildings up to a 100m2 foot print.

More than 100m2 buildings - The company has printed actual buildings with a footprint of more than 100m2.

Multiple storey buildings - The company has printed buildings with 2 floors or more.

Technology

Additive Manufacturing technology

Additive Manufacturing, also known as 3D Printing, is a group of machine technologies that share the similar feature of adding material to create/manufacture objects. The process usually starts from a 3D model of the object that is sliced into layers. This data is then given to the machine, which is able to deposit material in those same layers, one on top of each other, until the entire object is created.

Following the ASTM International standards organization and its Additive Manufacturing categorization as a general guide, the following categories can be considered at a construction scale:

Material extrusion (layered) - An additive manufacturing process in which the added material is selectively dispensed through a nozzle or orifice, creating filaments of material that are deposited into layers, one on top of the other.

Material extrusion (suspended) - A modified version of material extrusion, where the material hardens immediately after being dispensed through the nozzle, solidifying in midair, and attaching itself to the part extruded immediately before. This way it is possible to defy the effect of gravity, which is pulling the material to the ground, and create a suspended filament of the material that attaches onto itself, starting from a fixed point in the ground.

Binder jetting - An additive manufacturing process in which a liquid bonding agent is selectively deposited on top of a layer of powder materials in order to join them. This process is repeated for several layers, until reaching the whole height of the printed volume. It is usually done layer upon layer, where the remaining unbound powder material acts as support for each next layer.

Form freedom

One of the main features of 3D printing is a certain degree of freedom in creating complex shapes, which separates it from traditional techniques that usually imply simple shapes, such as lines, squares or circles at best. The degree of freedom can be divided into different categories:

2D freedom - The technology is only able to create shapes within a two dimensional plane. This can be compared to an inkjet printer, which is limited to the two dimensional freedom of the paper it prints on.

2.5D freedom - The technology allows to create shapes mostly in two dimensional planes that are stacked on top of each other through gravity. This allows either to create layers with the same shape on top of each other, or to stack smaller layers on top of larger layers, keeping each layer contained within the boundaries of the layer below. It is also possible to have slightly larger layers on top of smaller ones, by creating slightly overhanging structures, but that depends mostly on the characteristics of the printed material.

3D freedom - The technology creates objects in such way that it can produce material in any direction, including overhanging structures, as long as it has a previously printed section of the material on which it can attach the new printed section. This allows the material to branch out into all three dimensions, similarly to the growth of a tree.

Full 3D freedom - The technology allows the printed materials to be completely supported in all directions, usually by some form of supporting material. This way the object is embedded and surrounded by support material, meaning that it can be placed virtually anywhere inside printing space, completely defying gravity. It also allows for objects to be trapped within other objects, without a contact point between the two. The only consideration remains that once the support material is removed, all the object will immediately be subject again to gravity, and look for the nearest way to the ground, or any other firm support underneath.

Fabrication location

Construction elements don’t necessarily need to be created on the construction site, but can also be built on various other locations. Therefore, construction size 3D printing follows the same rules. There are several different categories, based on where the fabrication occurs:

In situ - The object is constructed directly in the place where it needs to stay, much like in traditional construction.

On-site prefabrication - The object or its components are printed in the proximity of their final position (next to or inside the construction site), and then placed into position. The environment can be partially controlled or sheltered, depending on the necessities and possibilities that the site offers.

Off-site prefabrication - The object or its components are printed in a controlled environment, away from the construction site, and then transported and assembled there. This process resembles traditional industrial prefabrication in construction, such as the production of prefabricated concrete elements, various bricks, fixtures, etc.

Partial prefabrication (Off- and On-site) - Some parts of the construction are prefabricated and then afterwards put into their final position, while the rest is constructed directly in place, at the construction site.

Fabrication approach

There can be several ways that the printer can use the printed material to create construction size objects. These include:

Direct fabrication - The printed object is the definitive construction itself, and no erection or assembly is required.

Semi-direct fabrication (parts are introduced) - The printed object is the definitive construction, but certain parts are added during the printing procedure, to facilitate the process or to overcome some physical obstacles. As an example, lintels can be installed where doors or windows will be, to simplify the printing of layers that need to go over them.

Component fabrication - The object is divided into components that are printed as separate parts. The parts are then assembled into the final object.

Formwork fabrication - The printed object acts only as a formwork to another material, such as concrete, that will be cast within. The printed object is removed afterwards. The formwork can be printed in parts or as a single object.

Stay-in-place formwork fabrication - As above, the printed object acts as a formwork for casting another material within, but remains in place, as an integral part of the construction. Usually, the printed material acts as a secondary structure, while the poured material is the primary load-bearing structure.

Cover/Engulfing fabrication - The exact opposite of the formwork fabrication, this process starts with a readymade supporting structure that is positioned into place. The printed material is then deposited around the supporting structure, and covers/engulfes it permanently.

Printer

Movement system

To be able to perform the printing procedure, the printer head needs to be moved around the printable surface. There are several movement systems, which include:

Cartesian gantry - The system is moved on a rectangular frame independently in 3 different directions, one for each axis: X (east and west), Y (north and south), and Z (up and down). Each independent movement direction can be performed differently, through rolling, pulling, pushing or similar, and each one requires at least one separate motor to activate the movement.

Delta gantry - The printer head sits on a suspended plate that is placed centrally between 3 vertical pillars. The suspended plate is connected to each of the pillars through a pair of arms that are allowed to move up and down along the pillars, independently. By pulling the arms up or down along the pillars, the suspended plate moves around the printer area, covering its whole surface.

Robotic arm - The deposition system is moved in all possible directions by the means of an articulated robotic arm. The arm uses several rotary joints in a variety of sequences, in order to perform every possible movement within its reach.

Mobile robotic vehicle - The deposition system is mounted on top of a separate vehicle capable of moving around a certain area or volume, through the use of its own motors. This can include climbing on top already printed parts, hovering in mid-air, or similar. The vehicle can be loaded with a certain amount of material and then refilled once empty or it can be constantly connected to a feeder, through a pipe/hose.

Cable suspension - Similar to the delta gantry, the system is suspended on three or more cables. The suspended plate is moved around by pulling or releasing the cables independently from each other.

Maximum printing volume

The maximum printable volume that the machine is able to produce.

The maximum size of the printable area

The maximum printable surface that the printer that the printer can print in.

Number of nozzles/orifices

The material in a 3D printer is usually deposited through one or more nozzles or similar orifices. These can usually be moved or rotated to reach the areas where the material needs to be deposited.

Single nozzle - most commonly, 3d printing technologies use a single nozzle which is then moved around to place the material everywhere where it is needed.

Multiple nozzles - the technology uses two or more nozzles, either to deposit different materials from each one of them, or to multiply the speed of the process.

Nozzle array - the technology uses a series of nozzles all placed in a row, and moving together. This way, instead of moving one nozzle in all directions to deposit the material, there can be several that are programmed to selectively deposit the material where necessary, and this way reduce the movements.

Deposition method

The materials can be pushed through the nozzle to the printable surface in a variety of ways:

Jetting - The deposition involves liquid materials, and is done by creating a pressure on the
material, usually through a pump, and depositing it at fast speeds on the printable surface.

Pressure extrusion - This method is the most common in 3D printing at large scale, and is
applied to very dense, partially fluid materials. As above, a pump creates a pressure on the
material, moves it through a pipe and slowly deposits on the printable surface or on the
previously extruded material.

Mechanical extrusion - Similarly to above, another common way of extruding materials is
through a mechanical push or drive, such as with an auger coil, or a piston.

Mechanical movement - The deposition is done by lifting and moving the material in
place, which makes it mostly suitable for solid materials.

Gravity deposition - The material is dropped onto the printable surface simply through the
use of gravity, which is mostly suitable for dense fluid or powder materials.

Sintering/welding - The materials are deposited into their position on the printable area,
and then subject to a high amount of energy, through laser, electricity, or similar sources.
This is able to produce a rapid increase in temperature and fuse/ weld the material in the
correct place, attaching it to the material deposited before.

Material feeding system

Before reaching the nozzle, the material needs to be delivered through it from a container, which
is also known as a feeder. These material feeding systems can be:

Manual - The material is fed to the nozzles manually, through an operator.

Included, semi-automated - – There is a feeding system for the material, which is mounted
on top of the printer. The system is not autonomous and needs an operator to activate or
control it

Included, fully-automated - There is an autonomous feeding system for the material,
which is mounted on top of the printer, and is fully commanded by the printer.

Separate, semi-automated – - – There is a separate feeding system connected to the printer
and located near it. The system is not autonomous and needs an operator to activate it or
control it.

Separate, fully-automated - There is a separate feeding system connected to the printer
and located near it. The system is fully autonomous, and the feeding is commanded by the
printer.

Nozzle diameter

This parameter indicates size of the nozzle through which the material needs to pass. It defines the
quantity and the size of material that can be extruded in every instant.

Theoretical printing speed

The maximum printing speed that can be achieved, if the whole printable area is used.

Actual printing speed

The actual printing speed is often reduced compared to the theoretical one, if the printing
technology involves also the printing of supporting structures. The value is estimated as a
percentage of the theoretical speed, by excluding the quantities of support material necessary in a
regular printing procedure for that machine.

Accuracy

This parameter defines the maximum error that the printer can make, or how much the physically
constructed print can deviate from the 3D model it has originated from.

Printer (diss)assembly speed

This parameter defines the time necessary to erect or dismantle the printer, depending on which
one is more time consuming

Price per printer unit

The price of each printer unit. If the company has different types of printers, the one described in
the report is considered.

Material

Material possibilities

The category defines how many materials can the printer use.

Single material - The printer is designed specifically for a single type of material.

Multiple materials - The printer can use different types of materials, either one at a time,
or simultaneously through the use of multiple nozzles.

Structure/Support materials - The printer is designed to use two separate materials, one
for the printed object, and one for support. It can print them one at a time, or both in the
same printing procedure. The peculiar feature of the two materials is that one is meant to
stay and become the final structure, while the other is designed to be removed after the
printing procedure is finished.

Material type

There are several types of materials suitable for 3DPrinting at a construction scale.

Traditional concrete - The most commonly used material, it includes all concrete material
that are based on standard cement (also known as Portland Cement).

Alternative concrete - All other types of concrete material that use alternative or less
common cements as their base material.

Clay

Soil

Plastic - All plastic materials, including those used in traditional desktop 3D Printers (such
as PLA or ABS)

Metal

Resin

Price

The price of material is referred to the final commercial price of a cubic meter of printed material.

Compression strength

Compression strength is a common characteristic of a material that defines its resistance to
pressure. It is measured as a resistance of a cube of material to failure (breaking), when subject to
a compressing force on two of its parallel surfaces. The value is calculated as the maximum
compression force before breaking divided by the area of one of the surfaces of the cube.

Tensile strength

Tensile strength is a common characteristic of a material that defines its resistance to
pulling/splitting forces. The strength is measured as a resistance of a cylinder of material to a
pulling force. The value is calculated as the maximum pulling force divided by the surface of the
middle transversal section of the cylinder.

Material verification

The level of verification of the material defines how well known are the characteristics and
behavior of the 3D printed material. These can be divided into:

Conceptual - The material has never been physically created or tested. There have only
been some conceptual predictions of its behavior or function.

Prototype - The material has been printed only a few times, mostly as preliminary tests to
attest the capabilities of the printer machine.

Partially tested - The material has been printed and tested a limited amount of times, to
identify some of its core characteristics.

Extensively tested - The material has been printed and tested several times. Its
characteristics are well-known and predictable.

Certified - The material has been tested according to standards, and has a certified
acceptance as a construction material with completely verified characteristics.

Material hardening time

Hardening time is an approximate time that is required for the material to become hardened
enough to be handled.

Material usability time

Usability defines the active time of the material, in which it can be deposited, before it becomes
unusable and needs to be replaced with a new active material.

Raw material price

The raw material price is the summed up commercial price of all the raw ingredients that are
contained in the printed material. This excludes the whole printing procedure, and all the
movements and treatments that are part of it, leaving only the value of the material itself.

Raw material availability

The availability of the raw material ingredients is focused mostly on the main ingredient of the
printed material that is the least available on the market, while still being very crucial for the
printing process. These can be divided into:

Industry standard - The material is one of the most important and well-known in the
industry, and is used in large quantities (such as concrete, steel, wood, etc.)

Extensively used - – The material is widely used in the construction industry, but in smaller
quantities than the industry standards.

Partially used - The use of the product within construction is limited, mostly to specialized
sectors and products.

Niche usage - The material is used very rarely in the construction industry, usually for very
specific and highly specialized products.